He did not elaborate on his comment and switched immediately to a prepared introduction of Springsteen.

"Bruce, you can rock the house like nobody else," De Niro said.

"And even more important in these perilous times, you rock the vote, always fighting for, in your own words, Truth, transparency, and integrity in government. Boy, do we need that now."

The expletive, known as the F-bomb, was bleeped by the CBS network for millions of television watchers at home.

However, it was heard by those in the audience and journalists covering the awards show, which honours the best of Broadway theatre, and it quickly became the top trending item on Twitter.

De Niro is one of the most respected actors in the United States with two Oscar wins for "Raging Bull" and "The Godfather: Part II."

"Mr. De Niro's comments were unscripted and unexpected," CBS said in a statement. "The offensive language was deleted from the broadcast."The White House did not immediately return a request for comment.

De Niro, a noted liberal, has been increasingly critical of Trump, a Republican, at smaller showbusiness events, but none have the high profile and audience of the Tony Awards.

The Tony Awards show was seen by some six million Americans last year.